Then I tried to update gems manually. Firstly:
> gem install cocoapods
ERROR: Could not find a valid gem 'cocoapods' (>= 0), here is why:
Unable to download data from https://rubygems.org/ - SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (https://s3.amazonaws.com/production.s3.rubygems.org/latest_specs.4.8.gz)
Great! That's the reason. There is a long long list of the issue under https://github.com/rubygems/rubygems/issues/515
The solution suggested are:
1. use an insecure connection to rubygems.org with:
> gem update --source http://rubygems.org
It works. But it doesn't solve the problem
2. RVM should update its certificates:
> rvm osx-ssl-certs status all
Certificates for /etc/openssl/cert.pem: Old.
> rvm osx-ssl-certs update all
Updating certificates for /etc/openssl/cert.pem: Updating certificates in '/etc/openssl/cert.pem'.
mkdir: /etc/openssl: Permission denied
Admin password required for 'mkdir -p /etc/openssl':
Then everything should be fine now.
A detailed information can be found at http://railsapps.github.io/openssl-certificate-verify-failed.html
For non-RVM and non-MAC users, here is the answer: http://stackoverflow.com/questions/19150017/ssl-error-when-installing-rubygems-unable-to-pull-data-from-https-rubygems-o